Where is it?

Shin Hazama is a normal high school boy living an ordinary life in Tokyo... a life that is about to be turned upside-down when he encounters Jin, a boy who looks identical to him but claims to originate from another world entirely.

Jin's world is one very different to our own - a world where an evil queen named Kotoko serves as its dictator, controlling all wealth and crushing any opposition with lethal force. Perhaps more importantly for Shin, the next step in Kotoko's plan for total domination is to expand her realm by invading his world, and with troops set to be dispatched imminently Jin's mission is to prevent this from happening and end Kotoko's reign forever.

The key to Jin's plan is the inextricable link between these "Relative Worlds" - if a person dies in one world, their doppelgänger in the other will also perish. So the race is on to find and assassinate the queen's other self in Shin's world - a mission that will draw him into an impossible moral quandary when the identity of the queen in his own world is revealed...